Arrup akiyoshiensis Tsukamoto & Shimano

Tsukamoto, Sho, Shimano, Satoshi, Murakami, Takashi, Hiruta, Shimpei F., Yamasaki, Takeshi & Eguchi, Katsuyuki, 2019, A new species of the genus Arrup from a limestone cave in Akiyoshi-dai, Western Japan (Chilopoda, Geophilomorpha, Mecistocephalidae), ZooKeys 830, pp. 33-51 : 36-41

Arrup akiyoshiensis Tsukamoto & Shimano sp. n. Figs 2, 3, 4, 5, 6, 7, 8, 9, Tables 3, 4, 5, 6

Type Material.

Holotype 1 female, Kagekiyo-ana, Mitou Town (Mitou-cho), Mine City (Mine-shi), Yamaguchi Prefecture, Japan, 30th of March 2018, coll. Takashi Murakami (labeled as TS-20180330-01). Paratype 1 female, Kagekiyo-ana, Mitou Town (Mitou-cho), Mine City (Mine-shi), Yamaguchi Prefecture, Japan, 18th of April 2018, coll. Takashi Murakami (labeled as TS-20180418-01).

Etymology.

The species name is derived from the name of Akiyoshi-dai Karst region, which includes the type locality.

Diagnosis.

Arrup akiyoshiensis sp. n. can be distinguished from the all named congeners by a combination of the following morphological characteristics: frontal line curved; seven pectinate lamellae in mandible; comma-shaped distal lobe of coxal projection in first maxillae; a tiny tubercle on outer-distal corner of each article of the telopodite; distal article of the telopodite of the second maxillae without claw; the well-developed tooth of forcipular article I; the triangular basal tooth in tarsungulum; the poison calyx overreaching forcipular article I; 31-35 pores on lateral and ventral sides on coxopleura.

Description.

Measurements of the holotype (adult female, TS-20180330-01) are followed by those of 1 paratype (adult female, TS-20180418-01) in parentheses. Body length 36.0 (34.5) mm, maximum body width 1.0 (0.95) mm, cephalic plate length 1.45 (1.30) mm, maximum cephalic plate width 0.92 (0.78) mm.

Antenna (Figs 2 A–E, 3 A–F, 7D, Tables 3-5) length 3.4 times as long as cephalic plate length. All articles weak areolate, except anterior margin; anterior margin of articles I to IV well areolate. Articles I to V slightly asymmetrical, with internal margin longer than external margin. Articles VI to XIV symmetrical. Setae on articles I to XIV spiniform, arranged uniformly (Figs 2 A–D, 3 A–D, Table 3). Distodorsal and distoventral surfaces of articles II, V, IX, and XIII with 1-7 small pointed sensilla (Fig. 2E, Table 5). Article XIV with 96-101 claviform sensilla on outer-lateral and inner-lateral sides (Figs 3 A–E, triangle in Fig. 3A, Table 4), with 6-9 pointed sensilla on the tip (Figs 3 A–D, F, arrow in Fig. 3A, Table 5).

Cephalic plate (Figs 4A, 8A) 1.5 times as long as wide. Transverse suture present. Paramedian sulci present. Lateral margins almost straight and convergent backwards; anterior margin convex; posterior margin straight. Surface areolated; proximal and distal scutes clearly marked. Setae arranged nearly symmetrically.

Clypeus (Figs 4B, 8B) 1.5 times as wide as long. Clypeal area absent. Paraclypeal sutures complete, strongly convergent backwards. Two clypeal plagulae not contacting with the paraclypeal sutures; remaining clypeal parts uniformly areolate, with setae arranged in two groups.

Labrum (Fig. 4C) consisted of three pieces. Side pieces divided into anterior and posterior alae with convexed chitinous line. Longitudinal stripes on the posterior alae absent. Anterior margin of side pieces almost straight. Internal margins of side pieces convergent backward, but not bordered directly with each other. Posterior margin of side pieces convex. Mid-piece 1.1 times as long as wide.

Cephalic pleurite (Figs 4B, 8C) with areolation entirely except a part of anterior region; scutes clearly marked along anterior margin, lateral margin, and paraclypeal suture. Spicula absent. Setae absent. Stilus well chitinized.

Mandible (Fig. 4D, Table 6) with seven pectinate lamellae. Lamellar teeth sharp; 2-15 teeth present in each lamella (Table 6); anterior tooth gradually longer than posterior one in each lamella.

First maxillae (Figs 4E, 8D) undivided, without mid-longitudinal suture in coxosternite, convergent forward; anterior corners not projecting; ventral surface areolate, except for anterior and lateral margins; setae absent. Coxal projection well developed, with six spines on each internal margin and 4-5 setae at the each middle position. Basal part of medial projection round, with distal lobe; distal lobe clavate as comma-shaped. Basal part 1.7 times as long as distal lobe.

Second maxillae (Figs 4E, 8D) undivided, without mid-longitudinal suture in coxosternite; 5 + 5 setae arranged along the anterior margin, 3 + 3 setae on lateral side. Isthmus areolate. Anterior and posterior margins concave. Lateral margins parallel. Telopodites triarticulated, reaching the telopodite of first maxillae. Claw of the telopodite absent. A tiny tubercle present on outer-distal corner of each article. Article I 2.8 times as long as wide; article II 1.6 times as long as wide; article III 3.2 times as long as wide.

Forcipular segment (Figs 5 A–D, 7B, C, 9A, B) with setae both on dorsal and ventral surface; setae arranged almost symmetrically. Coxosternite with distinct 1 + 1 projections in anterior margin. Chitinous lines absent. Forcipular tergite trapeziform. When telopodites closed, tarsungulum reaching anterior margin of cephalic plate. Article I 1.9 times as long as wide, with a well-developed pointed tooth at the distal internal corner. Article II 0.40 times as long as wide, with a tubercle at the internal margin (arrows in Fig. 5A, B). Article III 0.37 times as long as wide, with a tubercle at the internal margin. Tarsungulum with a triangular basal denticle. Claw of tarsungulum with numerous tiny sensilla. Calyx of poison gland overreaching article I. Duct opening of poison gland on dorsal tip of tarsungulum (triangle in Fig. 5C).

Leg-bearing segments (excepting last leg-bearing segment) (Fig. 6 A–D) without pore field on sternites. Median longitudinal sulcus present on sternites I–XVII. Forty-one leg-bearing segments in both the holotype and paratype. All legs weakly areolate. First pair of legs much shorter than the others. All leg claws with anterior and posterior accessory spines; posterior one with a subsidiary spine at its bottom (arrows in Fig. 6C, D).

Last leg-bearing segment (Figs 6 E–H, 9C, D) with numerous setae both on tergite and sternite; setae arranged almost symmetrically. Sternite as long as wide, sub-triangular, with posterior margin round. Tergite sub-pentagonal. Coxopleura with 31-35 pores on lateral and ventral sides. Telopodite having six articles, but without claw.

Postpedal segment (Figs 6E, F, 9C, D) with setae on each segment; setae arranged almost symmetrically. Female gonopod uniarticulate; distal part elongate. Anal pore opened laterally.

Coloration (Fig. 7A). Head and forcipular segment pale ocher; other body segments whitish yellow, without dark patches.

Distribution.

Known from only the type locality.

Type locality.

Kagekiyo-ana, Mitou Town (Mitou-cho), Mine City (Mine-shi), Yamaguchi Prefecture, Japan (34°17.50'N, 131°20.00'E).

Remarks.

Arrup akiyoshiensis sp. n. is morphologically similar to several other congeners, especially A. holstii (Pocock, 1895) and A. ishiianus Uliana, Bonato & Minelli, 2007 (Fig. 10), but can be easily distinguished from them by a combination of the characteristics shown in Table 7.